Subject: Re: CVS commit: src/sys/ufs/ffs
To: Ben Harris <bjh21@netbsd.org>
From: Perry E. Metzger <perry@piermont.com>
List: source-changes
Date: 03/23/2006 09:58:17
Ben Harris <bjh21@netbsd.org> writes:
> In article <20060323133853.GA1468@beta.martani.n2.repy.czf> you write:
>>On Thu, Mar 23, 2006 at 11:16:48AM +0000, Juergen Hannken-Illjes wrote:
>>> Log Message:
>>> ffs_balloc*(): Add an assertion for "bpp != NULL" if B_METAONLY is set.
>>
>>Why? bpp is immediately dereferenced, so if it is NULL, the kernel will
>>panic anyway.
>
> NULL dereferences in the kernel don't always cause panics.  In
> particular, read dereferences don't panic on some NetBSD/arm platforms,
> and even write dereferences don't panic on NetBSD/acorn26.

However, on most platforms, they do cause panics, and certainly such
dereferences are not "correct" code -- you are in an unknown state
once you've done such a thing.

Perry